Depositing bulk or micro-scale electrodes
Thicker electrodes are provided on microelectronic device using thermo-compression bonding. A thin-film electrical conducting layer forms electrical conduits and bulk depositing provides an electrode layer on the thin-film electrical conducting layer. An insulating polymer layer encapsulates the electrically thin-film electrical conducting layer and the electrode layer. Some of the insulating layer is removed to expose the electrode layer.
1. A method of fabricating an implant device, comprising the steps of:
depositing an electrically insulating polymer layer on a substrate,
depositing a conductive trace layer on said electrically insulating polymer layer wherein said conductive trace layer has a trace layer thickness,
depositing a bulk deposited electrode layer on a portion said conductive trace layer wherein said bulk deposited electrode layer has a bulk deposited electrode layer thickness and wherein said bulk deposited electrode layer thickness is thicker than said trace layer thickness,
thermocompressively bonding said bulk deposited electrode layer to said portion of said conductive trace layer using heat, pressure, and ultrasound,
depositing an encapsulating electrically insulating polymer layer on said conductive trace layer and said bulk deposited electrode layer,
removing at least a portion of said encapsulating electrically insulating polymer layer that covers said bulk deposited electrode layer exposing at least a portion of said bulk deposited electrode layer,
wherein the above steps produces the implant device, and
releasing the implant device from said substrate.
2. The method of fabricating an implant device of claim 1 wherein said step of depositing a bulk deposited electrode layer on a portion of said conductive trace layer comprises depositing a bulk deposited metal electrode layer on a portion of said conductive trace layer.
3. The method of fabricating an implant device of claim 1 wherein said step of thermocompressively bonding said bulk deposited electrode layer to said portion of said conductive trace layer using heat, pressure, and ultrasound is accomplished using a combination of pressure and elevated temperature with ultrasonic energy to bond said bulk deposited electrode layer to said conductive trace layer.
4. The method of fabricating an implant device of claim 1 wherein said step of thermocompressively bonding said bulk deposited electrode layer to said portion of said conductive trace layer using heat, pressure, and ultrasound is accomplished using a flip-chip bonder, die bonder, or diffusion bonder.
5. The method of fabricating an implant device of claim 1 wherein said step of depositing a bulk deposited electrode layer on a portion of said conductive trace layer comprises depositing a bulk deposited platinum metal electrode layer on a portion of said conductive trace layer.
6. The method of fabricating an implant device of claim 1 wherein said step of depositing a bulk deposited electrode layer on a portion of said conductive trace layer comprises depositing a bulk deposited niobium metal electrode layer on a portion of said conductive trace layer.
7. The method of fabricating an implant device of claim 1 wherein said step of depositing a bulk deposited electrode layer on a portion of said conductive trace layer comprises depositing a bulk deposited iridium metal electrode layer on a portion of said conductive trace layer.